> It looks a bit like a map of the Japanese islands, so optical engineers will often talk about "Hokkaido", "Tokyo" or "Nagasaki" glass. It is interesting; I w

> It looks a bit like a map of the Japanese islands, so optical engineers will often talk about "Hokkaido", "Tokyo" or "Nagasaki" glass. It is interesting; I wonder if (especially since so much of the glass in optical devices comes from Japan) these terms are pretty universally-applied in the lens-making industry. It's one of those things that makes perfect sense once you've seen both the chart and a map of Japan... but if not, you'd be quite puzzled.